Wizards have been an essential element of fantasy movies since the dawn of the cinema. Essentially, you can't hope to have a universe of dragons, trolls and adventurous men with names like "Numedor" without including a powerful wizard who is there to lend a magical hand when the going gets tough.
Unfortunately, not every wizard in film history has stepped up, and some seem to flat-out prefer cashing in their wizard pensions and spending the rest of their 2,000-year lifespan as the door greeter at Walmart than perform their expected duties.
Albus Dumbledore (the Harry Potter series)
Dumbledore is the headmaster at Hogwarts School of Witchcraft and Wizardry, and basically the most powerful damned wizard in the Harry Potter universe. He's a kindly old man, which is a good thing because he can turn invisible, create objects out of thin air, read minds, shoot fire, whatever. He's pretty much a god.
Unfortunately, most of the time he gives kind of boring speeches and makes a teenage boy do everything that he, being nearly all-powerful, should probably be doing instead.
The case against him:
Fans of the Harry Potter series have uttered the phrase "Where the crap is Dumbledore during all of this?" more than once. He's usually away on business when Harry and his friends are in imminent danger of attack, and the three of them are usually left to either figure out difficult riddles or single-handedly fight humongous snakes, a giant troll, an army of gigantic spiders--pretty much every horror imaginable. And when he says he's away on business, you know he's probably just hanging out in his apartment in his wizard underpants watching the wizarding equivalent of Frasier reruns.
Consider Prisoner of Azkaban, where in order to save a friend he casually advises Hermione to use a "Time Turner" device, which lets you effortlessly go back in time and change any thing you want.
Wait, what? Why didn't he go back in time and deal with it? Or better yet prevent all those things from happening with his wizard powers? Why not go back and prevent the birth of the wizard Antichrist, Voldemort? And in the 6th book, he actually dies. The man can travel through time, but he couldn't prevent his own freaking death?
Skeletor (Masters of the Universe)
Skeletor is He-Man's main nemesis in the Masters of the Universe TV show, comics and films. Essentially a nude, muscular Smurf with a yellow skull for a head, Skeletor is a highly-skilled sorcerer who wields one half of the "Power Sword." He-Man has the other half, and whoever unites the two will become, dare we say, the Master of the Universe.
The case against him:
If you're into nude men who like to ride around on giant cats then your entertainment options were pretty much limited to He-Man and the Masters of the Universe. As a fan you know that Skeletor was possibly the baddest guy on this or any other planet.
He was blue, wore nothing but some legwarmers, a mini-skirt and a pair of suspenders, and had an entire mysterious magical arsenal at his command. He could fire lasers out of his eyes, teleport and shoot lightning out of his hands. But most convenient of all, was that he possessed the power of 'remote viewing' which enabled him to sit around in Snake Mountain and cackle at a vision of He-Man and his fellow semi-nude male friends, remarking to henchman Beast Man how He-Man was 'about to fall into' a devious trap he'd set (devious in this case meaning "easily escapable").